This invention relates to medical methods, and more particularly to methods for use in making anastomotic connections between tubular body fluid conduits in a patient.
There are many medical procedures in which it is necessary to make an anastomotic connection between two tubular body fluid conduits in a patient. An anastomotic connection (or anastomosis) is a connection which allows body fluid flow between the lumens of the two conduits that are connected, preferably without allowing body fluid to leak out of the conduits at the location of the connection. As just one example of a procedure in which an anastomosis is needed, in order to bypass an obstruction in a patient""s coronary artery, a tubular graft supplied with aortic blood may be connected via an anastomosis to the coronary artery downstream from the obstruction. The anastomosis may be between the end of the graft and an aperture in the side wall of the coronary artery (a so-called end-to-side anastomosis), or the anastomosis may be between an aperture in the side wall of the graft and an aperture in the side wall of the coronary artery (a so-called side-to-side anastomosis (e.g., as in published Patent Cooperation Treaty (xe2x80x9cPCTxe2x80x9d) patent application WO 98/16161, which is hereby incorporated by reference herein in its entirety)). The graft may be natural conduit, artificial conduit, or a combination of natural and artificial conduits. If natural conduit is used, it may be wholly or partly relocated from elsewhere in the patient (e.g., wholly relocated saphenous vein or partly relocated internal mammary artery). Alternatively, no relocation of the graft may be needed (e.g., as in above-mentioned application WO 98/16161 in which a length of vein on the heart becomes a xe2x80x9cgraftxe2x80x9d around an obstruction in an immediately adjacent coronary artery). More than one anastomosis may be needed. For example, a second anastomosis may be needed between an upstream portion of the graft conduit and the aorta or the coronary artery upstream from the obstruction in that artery. Again, this second anastomosis may be either an end-to-side anastomosis or (as shown, for example, in above-mentioned application WO 98/16161) a side-to-side anastomosis. Alternatively, no second, upstream anastomosis may be required at all (e.g., if the graft is an only-partly-relocated internal mammary artery).
The currently most common technique for making an anastomosis is to manually suture the two tubular body fluid conduits together around an opening between them. Manual suturing is difficult and time-consuming, and the quality of the anastomosis that results is highly dependent on the skill of the person doing the suturing. In the case of coronary artery bypass procedures, one source of difficulty for suturing of an anastomosis may be motion of the heart. There is also increasing interest in procedures which are less invasive or even minimally invasive. Such procedures have potentially important advantages for patients, but they may increase the difficulty of performing manual suturing of an anastomosis by reducing or limiting access to the site within the patient at which the anastomosis must be made. Various examples of such less invasive or minimally invasive procedures are shown in above-mentioned application WO 98/16161, Goldsteen et al. U.S. Pat. No. 5,976,178, Sullivan et al. U.S. Pat. No. 6,120,432, published PCT patent application WO 98/55027, and Berg et al. U.S. patent application Ser. No. 09/187,364, filed Nov. 6, 1998, all of which are hereby incorporated by reference herein in their entireties.
In the case of making a conventional end-to-side anastomosis between a vein graft and the coronary artery, there are additional difficulties which may arise. First, the relative sizes of the coronary artery and the vein graft are different. For example, the coronary artery may typically have an inner diameter of about 1.0 to 3.0 mm, whereas a vein graft, such as the saphenous vein, may typically have an inner diameter of about 4.0 to 8.0 mm. This discrepancy between vessel diameters, i.e., a xe2x80x9ccaliber mismatch,xe2x80x9d may present a challenge to the physician to match the end of the relatively larger vein graft to an aperture in the side wall of the relatively smaller coronary artery. The resulting quality and amount of flow between the vein graft and the coronary artery, along with the provision of an effective hemodynamic seal between the two conduits, is often dependent upon the physician""s skill in making a precise and effective junction between the two conduits.
Second, conventional end-to-side anastomosis typically joins the vein graft conduit to the coronary artery at an angle with respect to the lumen of the coronary artery, thus forming a junction at the wall of the coronary artery. Further away from this junction, the vein graft tends to lie against the heart structure, or substantially parallel to the lumen of the coronary artery. The transition of the vein graft from a substantially perpendicular juncture to the coronary artery to a substantially parallel position with respect to the coronary artery wall often occurs abruptly, which may result in kinking of the vein graft, with possibly reduced blood flow.
Third, joining vessels having relatively small diameters (e.g., 1-4 mm) presents the additional consideration of keeping the vessels open after the anastomosis has been made. It is therefore helpful to provide the anastomosis with an diameter equal to or larger than the diameter of the smaller vessel being joined. The larger anastomosis is performed in order to minimize the risk of closing off the flow due to the natural healing response. However, it is a challenge to provide a delivery system which is compatible with the dimensions of the anastomosis.
There are additional difficulties which may arise in an anastomosis procedure between a vein graft and a coronary artery. Initially, an artificial aperture, called an arteriotomy, is created in the side wall of the coronary artery. The coronary artery is pressurized during the creation of the aperture. During the suturing of the vein graft to the aperture, excessive bleeding may occur as a result of the pressure in the coronary artery. Thereafter, if the artery is ligated to control the excessive bleeding, the distal areas of the coronary artery vessel may become ischemic which means that vital organs may not receive adequate oxygenated blood. The excessive bleeding may also interfere with the physicians visual ability to accurately suture the vein graft to the aperture.
Another minimally invasive procedure for an anastomosis is using an end-to-side adhesive technique. With this technique, the end of the vein graft is attached to an opening on the coronary artery using adhesive. However, end-to-side adhesive anastomosis techniques have been unsuccessful for many reasons. First, precise positioning of the end of the vein graft and the aperture in the side of the coronary artery is required before and during the application of the adhesive. Due to the caliber mismatch, great skill of the physician is required in making an effective junction between the two conduits. Secondly, the overlap area between the two conduits is inadequate to provide the necessary strength for an effective attachment. Also, the excess flow of adhesive may be difficult to control. Therefore, the excess adhesive may enter into the aperture and the blood flow. Finally, the coronary artery may require ligation to control the excessive bleeding resulting in the distal areas of the coronary artery vessel becoming ischemic as described above.
In view of the foregoing, it is an object of this invention to provide methods that can be used to make anastomotic connections in lieu of manual suturing.
It is another object of the invention to provide methods that can be used to make anastomotic connections wherein the aperture in the vein graft is the same size as the aperture in the coronary artery.
It is still another object of the invention to provide methods that can be used to make anastomotic connections without the need for a high degree of manual suturing skill.
It is yet another object of the invention to provide methods for making anastomotic connections that are less adversely affected than manual suturing by adjacent or nearby body motion (e.g., motion of the patient""s heart).
It is a further object of this invention to provide methods for facilitating the making of higher quality anastomotic connections more rapidly and with more consistent results than are possible with prior art methods and apparatus such as manual suturing.
It is another object of the invention to provide methods for making a high quality anastomotic connection when joining two conduits having different relative diameters.
It is yet another object of the invention to provide methods for making a high quality anastomotic connection having greater strength due to the overlap of the two conduits.
It is a further object of the invention to provide methods for making an anastomotic connection which does not require ligation.
It is another object of the invention to provide methods for making a high quality anastomosis which allows the conduits to be positioned in a substantially flat configuration with respect to one another (i.e., no angle between the vein graft and the coronary artery) and which prevents kinking of the conduits.
These and other objects of the invention are accomplished in accordance with the principles of the invention by providing methods for use in making an anastomosis connection between two tubular body fluid conduits in a patient.
An anastomosis technique is provided for facilitating cutting of an aperture in a first conduit and a second conduit of a patient. In a preferred embodiment of the subject invention, the first conduit is placed relatively adjacent to the second conduit at an operative site to make a side-to-side anastomosis connection.
A region is created where the first conduit and the second conduit are adjacent and contact each other. An adhesive is placed in a substantially two-dimensional area or region between the first conduit and the second conduit such that a substantially two-dimensional bonded area or region is created. The adhesive material is preferably highly bondable in a fluid environment.
The next step in the procedure is to create the aperture through the bonded region between the first conduit and the second conduit. The aperture is also preferably substantially two-dimensional, although smaller in area than the bonded region. A precisely controlled aperture size and geometry is needed to optimize the performance of the anastomosis. A diameter of the aperture is smaller than a diameter of the bonded region in order that after the aperture is created, the first conduit and the second conduit remain bonded and secured to each other annularly around the aperture.
A cutting instrument is provided for facilitating cutting the aperture in the bonded region of the two conduits. The cutting instrument may include a handle suitable for the physician performing the process to grip securely. The cutting instrument may also include a cutting mechanism that creates the aperture and removes the tissue in the bonded region. The cutting mechanism is inserted through an opening in a wall of the first conduit at an angle that is substantially perpendicular to a longitudinal axis of the second conduit and cuts the aperture in the bonded region. The tissue in the opening is re-attached using sutures once the cutting instrument is removed and the anastomosis procedure is completed.
The cutting mechanism may include a tissue holding structure, such as a stylet, which pierces and retains tissue, and a sharp-edged tubular structure, such as a rotatable coring tip, which cuts a plug of tissue retained by the stylet, thus providing the aperture for the anastomosis. The stylet may include a retention structure such as barbs for retaining the plug of tissue that is removed so that the tissue is prevented from entering the bloodstream.
In yet another preferred embodiment, the step of creating the aperture after the two conduits are connected may be utilized in an anastomosis procedure where conventional suturing techniques are used. The two conduits are manually sutured together in an end-to-side or side-to-side configuration. Once the two conduits are secured together, the aperture is formed using the steps discussed heretofore.